Inspiration banner

Continuous glucose monitors

A continuous glucose monitor (CGM) gives information about your glucose levels every few minutes

You can track whether your glucose is high or low, and see how your glucose levels vary, for example while you are sleeping, after you eat, when you exercise, or when you are feeling unwell.

How does a continuous glucose monitor work?

A CGM has three parts:

  • Sensor – this senses how much glucose there is in the interstitial fluid and is inserted into the skin. This is connected to the transmitter.
  • Transmitter – this is worn on the skin which communicates with the receiver (usually wirelessly).
  • Receiver – this records results and displays them on a pager sized device often worn on a belt or carried in a handbag. Systems that display immediate results are often called ‘real-time’.

The information CGMs provide is useful for analysing the trend of your glucose levels rather than the reading at any particular moment. It does not measure glucose in the blood, but glucose in something called the interstitial fluid (that’s the fluid between the cells under your skin). This means that the information is 5-15 minutes older than the reading you get from a fingerprick reading. None of the systems currently available are intended to be used in place of fingerprick testing but rather as an extra layer of information.

Research suggests that using a CGM can help reduce HbA1c without increasing the risk of a hypo. They can help you maintain target blood glucose levels, and limit the risk of hypoglycaemia if they are used on a daily basis (ie at least 80% of the time).

What features does a continuous glucose monitor include?

All current CGM systems have the following:

  • A display of current glucose level
  • A trend arrow indicating whether glucose is falling or rising
  • Trend information e.g. a graph showing results over the last three, six or 24 hours
  • Alarms to indicate high or low glucose or rapid change
  • Ability to download data and view graphs and statistics
  • Some systems provide early warning alarms if glucose levels are likely to fall too high or low.

Who supplies continuous glucose monitor systems in the UK?

There are currently various suppliers offering CGMs licenced for different age groups. Licenced for use by all ages, are:

  • Medtronic – as a separate system or linked to the Veo insulin pump. Medtronic also makes a system which records CGM readings for later reading on a computer, without displaying it to the wearer. It’s licenced for use in those aged 2 or older:
  • Animas – the Vibe insulin pump can be linked to a Dexcom system, It’s licenced for use in those aged 6 or older:
  • Abbott – as a separate system. This is licenced for use in those aged 18 or older:
  • Dexcom – as a separate system or linked to the Animas Vibe insulin pump

Type 1 Technology guide

We have produced a family-friendly guide to type 1 diabetes technology, which highlights recommendations from NICE on treatments and technology for children and young people with type 1 diabetes.

Click here to download

How do you get access to a continuous glucose monitor?

The NICE guideline recommends that children and young people are offered ongoing use of real-time CGM with alarms to young people with type 1 diabetes who have frequent severe hypoglycaemia or impaired awareness of hypoglycaemia associated with adverse consequences (for example, seizures or anxiety) or  inability to recognise, or communicate about, symptoms of hypoglycaemia (for example, because of cognitive or neurological disabilities).

In addition, the guideline recommends that ongoing use of real-time CGM should also be considered for other groups:

  • Neonates, infants and pre-school children
  • Children and young people who undertake high levels of physical activity (for example, sport at a regional, national or international level)
  • Children and young people who have comorbidities (for example anorexia nervosa) or who are receiving treatments (for example corticosteroids) that can make blood glucose control difficult.

The guideline also recommends considering occasional use of CGM to help children and young people to improve their glucose control especially for those who continue to have hyperglycaemia despite insulin adjustment and additional support.

The NHS is not legally obliged to provide funding for CGM. However, the guideline makes a strong recommendation for CGM to be used with children who are unable to recognise or communicate about hypo symptoms. This includes very young children who cannot tell you they are having a hypo even if they recognise it.

If you cannot get NHS funding, you may want to consider self funding. You do not need a prescription to use CGM, you can buy a system direct from the company. However you are likely to get most benefit from the system if you get support in using it, so do ask what support the company and your diabetes team can give you.

There are two costs associated with CGM:

  • The initial cost – for the hardware such as the receiver and transmitter – varies from around £1,000 to £2,500. If you have a newer Medtronic or Animas Vibe pump you may find CGMS is already integrated or may be available if you pay a supplement (around £200).
  • Running costs – The main on-going cost is the disposable sensors, costing around £40 – £60 per sensor, with each sensor lasting a recommended 5 – 7 days. Many users find they can wear their sensors for longer than the recommended number of days.

In some cases you also need adhesive covers to keep the sensors in place or protect them from water. You may also need to buy semi-disposable components such as transmitters every 9-18 months or so.


Some of the information above was kindly provided by INPUT, a patient-run group for people using or wishing to use insulin pumps to control their diabetes. Visit for more information.

NHS review on continuous glucose monitors for pregnancy

NICE has agreed to review its diabetes in pregnancy guidelines focusing on continuous glucose monitoring (CGM) for pregnant women with type 1 diabetes in England

What do we know about flash glucose monitoring?

Using a FreeStyle Libre can lead to fewer hypos and improved HbA1c levels, found a recent study reviewing the current evidence on the device.